/* 
接口可以描述函数类型
限定函数的参数和返回值的类型
*/
interface searchFnInter {
  (x: string, y: string): boolean
}
const searchFn: searchFnInter = (a: string, b: string): boolean => {
  return  a.includes(b)
}

console.log(searchFn('abcd', 'bc')) // true